fix(989): correct four live build-log viewer bugs in logs.js

- live detection: use !h.status (null while running) not === 'running'
- SSE: replace named addEventListener('chunk'/'done') with onmessage +
  frame.done check — backend sends generic message events, no named type
- SSE payload: use frame.stdout_append/stderr_append not frame.text
- timestamps: started_at/finished_at are unix seconds, multiply by 1000
  was already done implicitly — actually use unix arithmetic directly
  to avoid new Date() confusion entirely

Also move the misplaced .flow-main-slim rule from the logs section to
the flow-shell section of dashboard.css.

frontend/packages/dashboard/src/dashboard.css

@@ -1805,6 +1805,11 @@ body.flow-shell .tabbar .tab.active.tab-link {
   bottom: 0;
   overflow: hidden;
 }
+/* flow.html now has a slim header (back link only) instead of the full
+   tabbar — reduce the top padding to match the smaller header height. */
+body.flow-shell .flow-main-slim {
+  padding-top: calc(var(--flow-header-h) + 0.4em);
+}
 .flow-main .terminal-wrap {
   position: absolute;
   inset: 0;
@@ -1864,9 +1869,6 @@ body.logs-shell {
   margin: 0;
   padding: 0;
 }
-body.flow-shell .flow-main-slim {
-  padding-top: calc(var(--flow-header-h) + 0.4em);
-}
 
 .logs-header {
   position: sticky;

frontend/packages/dashboard/src/logs.js

@@ -40,13 +40,11 @@ import {
 
   // ─── helpers ──────────────────────────────────────────────────────────
 
-  function fmtTs(isoStr) {
-    if (!isoStr) return '';
-    try {
-      const d = new Date(isoStr);
-      const age = Math.floor((Date.now() - d.getTime()) / 1000);
-      return fmtAgeSecs(age) + ' ago';
-    } catch { return isoStr; }
+  // started_at / finished_at are unix seconds (i64), not milliseconds.
+  function fmtTs(unixSecs) {
+    if (!unixSecs) return '';
+    const age = Math.floor(Date.now() / 1000) - unixSecs;
+    return fmtAgeSecs(Math.max(0, age)) + ' ago';
   }
 
   function fmtDuration(secs) {
@@ -76,10 +74,11 @@ import {
       const ul = el('ul', { class: 'build-logs-list' });
       for (const h of rows) {
         const li = el('li', { class: 'build-logs-item' });
+        // status is null while running, 'ok'/'fail' when finished.
+        const live = !h.status;
         const ok = h.status === 'ok';
-        const live = h.status === 'running';
-        const statusClass = ok ? 'build-logs-ok' : live ? 'build-logs-live-badge badge badge-running' : 'build-logs-fail';
-        const statusLabel = ok ? '✓' : live ? 'live' : '✗';
+        const statusClass = live ? 'badge badge-running' : ok ? 'badge badge-ok' : 'badge badge-fail';
+        const statusLabel = live ? 'live' : ok ? 'ok' : 'fail';
         const age = h.finished_at ? fmtTs(h.finished_at) : (live ? '' : fmtTs(h.started_at));
         const runtime = h.runtime_secs != null
           ? el('span', { class: 'build-logs-runtime meta' }, fmtDuration(Math.max(0, h.runtime_secs)))
@@ -125,20 +124,35 @@ import {
             const badge = el('span', { class: 'build-logs-live-badge badge badge-running' }, 'live');
             detail.append(badge, pre);
             streamEs = new EventSource('/api/build-logs/id/' + h.id + '/stream');
-            streamEs.addEventListener('chunk', (e) => {
-              try { pre.textContent += JSON.parse(e.data).text; } catch { /**/ }
-            });
-            streamEs.addEventListener('done', () => {
-              badge.textContent = 'done';
-              badge.className = 'build-logs-live-badge badge';
-              streamEs.close(); streamEs = null;
-              detail.dataset.loaded = '1';
-            });
-            streamEs.addEventListener('error', () => {
-              badge.textContent = 'stream error';
-              badge.className = 'build-logs-live-badge badge';
-              streamEs.close(); streamEs = null;
-            });
+            let stdoutLen = 0, stderrLen = 0;
+            streamEs.onmessage = (e) => {
+              let frame;
+              try { frame = JSON.parse(e.data); } catch { return; }
+              if (frame.stdout_append) {
+                pre.textContent += frame.stdout_append;
+                stdoutLen += frame.stdout_append.length;
+              }
+              if (frame.stderr_append) {
+                if (stderrLen === 0) pre.textContent += '\n--- stderr ---\n';
+                pre.textContent += frame.stderr_append;
+                stderrLen += frame.stderr_append.length;
+              }
+              if (frame.done) {
+                badge.className = frame.status === 'ok' ? 'badge badge-ok' : 'badge badge-fail';
+                badge.textContent = frame.status || 'done';
+                streamEs.close(); streamEs = null;
+                detail.dataset.loaded = '1';
+              }
+            };
+            streamEs.onerror = () => {
+              if (streamEs && streamEs.readyState === EventSource.CONNECTING) {
+                pre.textContent = ''; stdoutLen = 0; stderrLen = 0;
+              } else {
+                badge.textContent = 'stream error';
+                badge.className = 'badge badge-fail';
+                if (streamEs) { streamEs.close(); streamEs = null; }
+              }
+            };
           } else {
             const pre = el('pre', { class: 'build-logs-output' }, 'fetching…');
             detail.append(pre);